Solid electrolytic capacitors (e.g., tantalum capacitors) have been a major contributor to the miniaturization of electronic circuits and have made possible the application of such circuits in extreme environments. Conventional solid electrolytic capacitors may be formed by pressing a metal powder (e.g., tantalum) around a metal lead wire, sintering the pressed part, anodizing the sintered anode, and thereafter applying a solid electrolyte. Intrinsically conductive polymers are often employed as the solid electrolyte due to their advantageous low equivalent series resistance (“ESR”) and “non-burning/non-ignition” failure mode. Such electrolytes can be formed through in situ polymerization of the monomer in the presence of a catalyst and dopant. Alternative, premade conductive polymer slurries may also be employed. Regardless of how they are formed, one problem with conductive polymer electrolytes is that they are inherently weak, which can sometimes cause them to delaminate from the dielectric during formation of the capacitor or during its operation. Furthermore, in very high voltage applications, the quality of the dielectric layer may cause failure of the part. For example, high voltage power distribution systems deliver a high voltage to the capacitor that can result in an inrush or “surge” current, particularly during a fast switch on or during an operational current spike. The peak surge current that the capacitor can withstand without failure may be in part related to the quality of the dielectric. Because the thinner areas have a lower resistance than the thicker neighboring areas, the power dissipated in the thinner areas is generally greater. Therefore, when a surge current is applied, these thinner areas may develop into weak “hot spots” that ultimately lead to degradation and breakdown of the dielectric.
As such, a need currently exists for a solid electrolytic capacitor having improved performance in very high voltage environments.